# Pre-Algebra : Circumference of a Circle

## Example Questions

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### Example Question #263 : Geometry

Becky's house is surrounded by a circular lake that Becky runs around each day. If Becky wants to figure out the distance she runs around the lake, what formula should Becky use?

Possible Answers:

None of the other answers

Correct answer:

Explanation:

Becky should use the circumfrence formula to find the distance she runs of a lake.

Correct Answer:

### Example Question #2 : Perimeter

What is the circumference of a circle with an area equal to ?

Possible Answers:

Correct answer:

Explanation:

Using the area, solve for the radius:

Divide by :

Take the square root:

Plug this radius into the formula for the circumference:

### Example Question #1 : Know And Use The Formulas For The Area And Circumference Of A Circle: Ccss.Math.Content.7.G.B.4

What is the circumference of a circle with a radius equal to ?

Possible Answers:

Correct answer:

Explanation:

The circumference can be solved using the following equation:

### Example Question #1 : Circumference Of A Circle

What is the circumference of a circle with a radius of ?

Possible Answers:

Correct answer:

Explanation:

The circumference can be solved using the following equation:

Where  represents the radius. Therefore, when we substitute our radius in we get:

### Example Question #5 : Know And Use The Formulas For The Area And Circumference Of A Circle: Ccss.Math.Content.7.G.B.4

The perimeter of a given rectangle is equal to the circumference of a given circle. The circle has radius  inches; the width of the rectangle is  inches. What is the length of the rectangle?

Possible Answers:

inches

inches

inches

inches

inches

Correct answer:

inches

Explanation:

The circumference of a circle with radius  inches is

inches.

The perimeter of the rectangle is therefore  inches. To find its length, substitute  and  into the equation and solve for :

inches

### Example Question #264 : Geometry

Determine the circumference of the circle if the radius is 20.

Possible Answers:

Correct answer:

Explanation:

Write the formula for circumference.

Substitute the radius and solve.

### Example Question #2 : Circumference Of A Circle

Given the area of the circle is , what is the circumference of the circle?

Possible Answers:

Correct answer:

Explanation:

Write the formula for the area of a circle.

Substitute the area.

Write the circumference of the circle.

Substitute the radius.

### Example Question #6 : Perimeter

Find the circumference of a circle with an area of .

Possible Answers:

Correct answer:

Explanation:

Write the area formula in order to find the radius.

Substitute the area.

Write the circumference formula.

Substitute the radius.

### Example Question #2 : Circumference Of A Circle

Determine the circumference of the circle if the radius is .

Possible Answers:

Correct answer:

Explanation:

Write the formula for the circumference of a circle.

Substitute the radius into the formula.

### Example Question #3 : Circumference Of A Circle

Find the circumference of a circle with a radius of .

Possible Answers:

Correct answer:

Explanation:

Write the formula to find the circumference of a circle.

Substitute the radius.

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